If you're shopping for an 80 series, there is no better resource that ih8mud.com and check out the FAQ.
I have owned my 80 series for about 18 years and it has been reliable for me, but really I may not be the right one to ask because I am a little bit crazy when it comes to catching problems before they become problems.
The main issue you'll find is the Head Gasket, everyone seems to be concerned about that. It does have a higher incidence of failure, but it's a pretty easy fix if it hasn't been done on one you find.
If you can get a vehicle that has service records, that's great, and that applies to any vehicle you buy.
A lot of 80's are still going from the first owner, Soccer Mom/Mall Crawler duty, so they need to be baselined, which means simply to check/change all bodily fluids, gear oils, etc.
Good luck, they're an awesome vehicle.